CESVA SC-30, Руководство пользователя, Страница: 53 / 76

SC-30
User’s Manual
51








⋅ =
∫
T
0
2
0
2
0
E
dt
p
(t) p
T
1
log 10 L
p(t): instantaneous sound pressure
p
0
: reference sound pressure (20
µ
Pa)
T: duration of the measurement
T
0
: 1 second
6.2.6 Percentile levels
L
99
, L
95
, L
90
, L
50
L
10
,
L
5
and L
1
These are the levels that were exceeded during 99%, 95%, 90%, 50%,
10%, 5% and 1% of the analysis time, in decibels.
The
L
AF
function is used to calculate them.
In some English speaking countries, the percentile levels are known as
the exceedence levels, or the statistical levels, or simply as L
n
values,
where ‘n’ is a number from 0.1 to 99.9.